He would get crushed. Nobody in the 2000s still fought like Tommy Burns or James Jeffries. He would be tested against much bigger and more athletic men. I see Michael Grant utterly dominating him. He might get past the Franz Bothas or Andrew Golota's of the world, may be even beats Lou Savarese, but that's about where it ends
In many ways it would be much easier. He would have a lengthy amateur career, he would have a manager from his pro debut, he would not have to take fights at short notice, and he would have a myriad of belts and weight classes to choose from. The only sense in which it could be harder, is if the men that he had to meet top get to the very top were better.